The Microbiology of Exposed Areas of Aquatic Habitats of Northern Ellesmere Island

Abstract

It has been known for many years that the soils and waters of the North American Arctic contain a great variety of microbes, such as fungi, bacteria, actynomycetes, myxobacteria and algae. ... The present paper constitutes a report on the microflora in exposed areas of shorelines of ponds and tarns located near Hazen Camp (81 49, 71 18 W), northern Ellesmere Island. ... All of the samples with two exceptions, had pH values on the alkaline side. Their carbon-to-nitrogen ratios varied from 8 to 29, such values are not being outside the range for many soils. When the conductivity measurements were converted into salinity classes, 22 per cent of the pond samples (nos. 2, 23C, 32 and 41) were found to be slightly saline; 17 per cent (nos 20, 26 and 45) moderately saline; and the remainder (61 per cent) strongly saline. Wide variations in numbers of microorganisms were observed, as indicated in Table 1. Salt concentration, pH and carbon-to-nitrogen ratio had no effect on the numbers; and, except possibly in the case of Cytophaga, temperature of incubation appeared to have no effect on them either. Numbers of Cytophaga tended to decrease somewhat as the temperature decreased. Holding et al and Parinkina also found fluctuations in the microbial counts for tundra sites, and there was no evidence that temperature was responsible for them. In contrast the situation found in studies dealing with cool-temperature regions of Canada, the number of fungal genera in the samples from the Arctic now being discussed was low, only eleven being identified. A similar paucity of fungal genera was noted by the present author in his study of four permafrost soils from the Mackenzie Valley. In the same study, the dominant fungal genus was Chrysosporium, to which an average of 45 per cent of all isolates belonged; the next most populous was Penicillium, which accounted for 20 per cent, and then Mortierella with 16 per cent. Phialophora, Cladosporium and Phoma each accounted for 4 per cent ofthe total isolates, and sterile mycelia 3 per cent. The remaining four genera (Oidiodendron, Cephalosporium, Coniothyrium, Gliomastix) were isolated with a frequency of 2 per cent or less. These results are similar to those of Dowding and Widden who, after assembling data from 33 tundra sites, found the most widespread fungal genera to be the sterile forms Penicillium, Chrysosporium, Cladosporium and Mortierella. It was also observed in the course of the study that, as the incubation temperature decreased, Chrysosporium was recorded far more frequently. This genus was represented by a single species C. pannorum, which is often abundant in cold environments and appears to be an important colonizer of such habitats. Since there are many more environmental parameters affecting microbial activity and numbers than were examined in this investigation, it would be difficult to discuss the relationship of the results to the High Arctic ecosystem. Nevertheless, if one keeps in mind that a large proportion of tundra mycoflora are psychrophilic and most of the nutrients in dead plants are released by microbes to aid growth of future vegetation, it becomes obvious that the presence of viable microbes in these lake shorelines, situated approximately 600 miles south of the North Pole, is very important. They are undoubtedly not only active in supplying plant nutrients but are helping to transfer part of the decaying vegetation to produce "stable" hummus which take part in the formation of the underlying and surrounding weakly-developed soil profiles. They also play an additional role in providing food for larger organisms, for Whittaker found that in Arctic sites the population peak for mites, follows that for fungi.